Means for controlling shot patterns



Oct. 18,` 1949.

Filed June 26, 1946 G. E. HUTcHlNsoN MEANS FOR CONTROLLING SHOT PATTERNS 2 Sheets-sheet 1 PAT TERN o) DDD LSD

v ENT AREA (SQUARE INCHES) GILBERT E. HU TCH/NSUN IN V EN TOR.

AT TURNEYS Oct. 18, 1949. G. E. HuTcHlNsoN 2,484,998

MEANS FOR CONTROLLING SHOT PATTERNS Filed June 26, 1946 2 Sheets-Sheet 2 .nga

INVENToR. GILBERT E, l-/UTcH/NsU/v A T TURNE Ys Patented Oct. 18, 1949 MEANS FOR CONTROLLING SHOT PATTERNS Gilbert E. Hutchinson, Bridgeport, Conn., as-

signor to Remington Arms Company, Inc., Bridgeport, Conn., a corporation of Delaware Application June 26, 1946, Serial No. 679,550

11 Claims. (Cl. 42-79) This invention relates to an improved method of controlling the pattern of the shot projected by a shotgun and to apparatus which may be applied to any shotgun to produce any desired concentration of pattern.

Different uses to which a shotgun may be put naturally require diierent pattern characteristics. For example, swiftly moving upland game at short range, pheasants, grouse in heavy timber, or the clay targets in the shoot game Skeet, require comparatively open or widespread patterns. Such patterns are necessary because even the most expert shots have difficulty in taking exact aim under such conditions andthe range is generally so short that a concentrated pattern would be highly destructive to game. While the disintegration of a Skeet target into black dust by a highly concentrated pattern may be regarded by the expert as a sporting and highly satisfying test of his skill, the same effect upon game is tragic and wasteful. At the other end of the scale, handicap trap shooting and the shooting of ducks and geese require relatively concentrated patterns. These are long range sports and if the gunner is to be given an even break in such tests of his marksmanship, he must be assured that, at the effective range, his pattern is still sufficiently concentrated to operate electively upon any target Within the pattern area.

The pattern of a shot charge is usually expressed in terms of arbitrary designations such as full choke, modified choke, improved cylinder, and the like. 'I'hese terms may be dened by reference to a percentage iigure which indicates the proportion of the total number of pellets in the charge which strike within the area encompassed by a thirty-inch circle on a target at a range of 40 yards. The normal range of requirements extends from an open or cylinder pattern which will place about 40% of the pellets in the thirtyinch circle at 40 yards to a full choke or close pattern in which about 7 0% of the pellets fall within the same circle.

In the fixed and variable pattern control devices of the prior art, the approach to the problem has been by way of constricting a short section of the barrel adjacent the muzzle. According to various theories of choke action, the constriction applies to the pellets a velocity compo nent directed toward the barrel axis which opposes and at least to some extent overcomes their natural tendency to diverge from that axis due to Various causes. Another theory of choke aotion is based upon the idea that the wad column is momentarily retarded by the choke and is therefore unable to act upon the base of the unsupported shot string ater emergence from the muzzle and exert an upsetting action thereon. Regardless of the theory involved, it has been the practice to produce more concentrated patterns by the use of muzzle sections constricted to a diameter less than that of the rest of the barrel. Since the entire range of constriction diameters between a normal 12-gauge true cylinder barrel and a full choke barrel of the same gauge is about 0.035 inch, and since the pattern variation is not directly proportional to constriction, it may be seen that conventional methods of pattern control must be-operated at extremely close tolerances.

It is the object of this invention to provide a means of pattern control which is operable throughout the range of desirable patterns and in which the critical factor may be readily and predictably controlled.

It is a further object of this invention to provide eiective, positive means of variable pattern control which will permit a single gun to be used for all types of shooting.

An additional object of this invention is the production of an elective pattern control device having a recoil equalizing feature.

The accomplishment of these objectives has been made possible by studies based upon the principle that when a short charge passes through a choke with a relatively long constriction, the charge conguration (and hence the pattern) can be altered by varying the amount of powder gas escape to the rear of the constricted section. The extent of gas escape can be readily controlled by the provision of escape vents of variable area which will permit the gas to escape from behind the wad column. Such principles may, of course, be utilized in the design oi barrels for any predetermined pattern or for the design of adjustable pattern control devices applicable to any gun.

The exact nature of the invention as well as other objects and advantages thereof willbecome apparent from consideration of embodiments thereof described in the following specication and shown in the accompanying drawings in which:

Fig. 1 is a longitudinal sectional view through a rudimentary form of the invention adjusted to produce cylinder patterns.

Fig. 2 is a similar view with the invention adjusted to produce full choke patterns.

Fig. 3 is a graph in which vent areas for the Figs. 1 and 2 illustrate the invention in a form simplified for discussion purposes to Vlittle `more than bare essentials. Referring thereto yby characters of reference, it may be seen that there is illustrated a cylinder barrel I which is formed with a recessed section 3 in which `there are vents 4. The recessed section is followed by an integral choke tube 5 having a throat `(i tapered at substantially 4the usual choke angle and a constricted section 'l of preferably not less than 6 inches in length and preferably of not greater inside diameter than the cylinder` bored barrel. The constricted section may be cylindrical or it may yflare slightly but in the latter event must not nare to an extent which willprevent the wad column from maintaining control over the escape of gas. Rotatably mounted on the recessed section is the control sleeve 8 having -vents 9 Which may be rotated into registry with the vents il o r may be positioned through an intermediate .range to a second extreme position in which the vsolid `portions of the sleeve 4completely close thevents 4. 4The first extreme position is that shown in Fig. 2, wherein all vents are open, and the -second extreme position is that shown in Fig. 1, wherein all vents are closed. In the intermedi-ate ranges the degree of opening of the partially exposed vents is directly controlled by the rotation of the sleeve.

As ,shown in Fig. 3, a vent area of `0.00 square inches (corresponding to the` position of Figv l) yields a pattern between 49% and 45%. This pattern will qualify as a good cylinder pattern. At this setting of the device', the shot col-umn emerges from the cylinder section o f the barrel, may spread slightly i n the recessed section, and may be reconstricted in the choke throat. Under closed vent conditions, the wad column-is under acceleration as it passes through the cons-tricted tube and by engagement with the base of the shot string recompacts the shot into a sufficiently solid body to allow the upsetting action just beyond the muzzle which is characteristic of cylinder patterns. Unless the constricted section of the choke tube is of substantial length, it will not be possible for the acceleration of the wad colurnn to recompact the shot string adequately for true cylinder proportions. Swix inches appears to be about the minimum length at which anaadequately open cylinder pattern may ber achieved,` while from 'Z1/2 to 8 inches seems to be better if such a length can be utilized without appearing disproportionately long or exerting an undesirable eiect on gun balance or feel.

The maximum internal diameter of the cylindrical constricted section is of some importance in that `a diameter materially larger than that of the cylinder barrel will produce inadequate reconstriction for a desirable full choke pattern and there may be sulcient gas ieakage to prevent adequate reacceleration of the wad column to effect the desired recompacting for a cylinder pattern. Thus, a substantially greater inside diameter than that of the barrel may have an undesirable effect at both ends of the scale of patterns. The inside diameter of the vented sectionisnot, critical so long vas it equals or exceeds the diameter of the barrel.

Regardless of whether or not the theories expressed above or to be expressed in regard to .operational principles are correct, it has been dennitely established that a construction of this type, adjusted as shown in Fig. 1, will produce adequate .cylinder patterns. It has likewise been established that the position of the sleeve shown in Fig. -2 vwill produce close patterns of normal or 'better ,than normal full choke proportions and that` lintermediate settings will produce intermediate patterns.

In the position shown in Fig. 2, all vents are open and as shown by the graph of Fig. 3, Va vent area of approximately 1.5 square ,--,IlGhes corre:- sponds to the conventional full choke or pattern. By the use of increased vent areas,lsome small additional improvement in the `field of extra full choke patterns may be obtained. As vwill be notedythe curve in this region is substantially at.

With this settingof the device.. the shot string emerges from the cylinder sec-tion of the barrel proper and those portions of thecharge having arelatively great spreading tendency may contact the choke throat and be realigned in-the final constricted section. The majordiierence, vhow-- ever, between this setting and that previously discussed and shown in Fig. 1, is that the propelling gases are relatively free to escape through the vents.v Thus, the propelling force behind-the wad column is largely dissipated and retardation `of the wad column by the choke throat will effectively prevent the recornpacting of the shot string into cylinder pattern configuration. The maximum concentrationof pattern which may be obtained in this manner will be obtained when the Vent area is adequate to relieve enough of the gas to completely prevent the wad column from reeontacting the base of the shot string.

The intermediate settings, as shown by the graph, produce intermediate patterns. It may be noted, for example, that the change from a 70% or full choke pattern to a 60% or modified choke pattern may be made by varying the v ent area from about` 1.5 square inches to about .70 square inch. With the conventional chokes, this theo retical variation in pattern would have been accomplished by a change in constriction diameter of about .015 in ch and the exact value would have been quite critical. Because of the non-linear characteristic of these control methods, the change between the more open patterns would have been much more critical. kObviously. an areawof more VAthan three quartersgof a square inch is a much more readily controllable factor, from a manufacturing or iield adjustmentpoint of o view, than a diametral change of a few thousandths of an inch.

Fig. 4 shows an embodiment of the invention designed as an attachment for an existing gun.` While its principle of operation is identical, its construction is slightly different. This embodiment is designed to be threadably or otherwise Securely attached t0 the muZzleQf a Cylinder bored barrel I I. Threadably attached to a con- Hector `l2 and extending forwardly therefrom is,

the vent tube la provided with a plurality of vents I4. The forward end of the vent tube has a threaded connection with a choke tube I5 which is bored internally to provide a conventional choke throat I6 and a constricted portion I'I of not more than barrel diameter. Slidably received on the exterior of the vent tube is a control sleeve I8 which may be moved longitudinally thereon and retained in the desired position by any suitable detent means to regulate the number of the vents I4 which are exposed and free to discharge gas.

This embodiment functions exactly as do those previously described. Briefly, the shot string emerges from the muzzle of the barrel, may expand slightly. in the vented section, is realigned by the choke throat, and, if the vents are closed, isV recompacted by the wad column to issue as a cylinder pattern shot string. If the vents are all open, the same sequence is followed but there is no recompacting action of the wad column and the shot string will issue with the elongated conformation essential to a close or full choke pattern.

The modified form of the invention illustrated in Figs. 5 through 8 combines with those principles previously discussed herein the elect which is the subject of a copending patent application of Walter L. Finlay, entitled Firearms, Serial Number 586,303, led April 3, 1945.

Fig. 5 illustrates the essentials of this form of the invention in a simplied form adequate for discussion of the principles of operation. Referring to that figure by characters of reference, it will be seen that a cylinder barrel 2I has slidably received on its exterior surface a sleeve 22 which is shown integral with a vent tube 23 provided with a plurality of vents 24. Leading forward from the vent tube is the choke tube 25 bored internally with substantially a conventional full choke taper 26 which terminates at the rear end of an elongated constriction 21, preferably not less than 6 inches in length and preferably of no greater diameter than the inside diameter of the barrel 2 I. The dimensions of the choke tube are subject to the same limitations as the modification previously discussed.

Adjustment of this modification is very simply achieved by longitudinal movement of the sleeve 22 on the barrel 2 I. Such movement, to the rear, for example, simultaneously reduces the elective area of the gas vents and shortens the length of the recessed section in which the shot string is not restrained against lateral spreading. The latter eiTect is that discussed in the copending patent application above identified, and for purposes of pattern control these effects are additive in nature.

The functioning of this modication is, in general, the same as that of the modification rst discussed. The charge emerges from the cylinder barrel, expands in the vented section, and is reconstricted by the choke throat. The amount of expansion and hence the amount of reconstriction necessary to bring the charge back to bore diameter are functions of the length of the recessed section as discussed in the copending application referred to herein. With all of the vents open and with the maximum length of recessed section, the wad column will not have suicient driving force to recompact the charge in the choke tube and the shot string will issue in the elongated form essential to the production of a full choke or close pattern. With rearward settings of the sleeve, the vent area is progressively reduced as the length of the recessed section is reduced. Thus, there is less opportunity for the charge to expand, the realignment will therefore be less severe, and there will be higher gas pressure to act upon the wad column and force it to recompact the charge into the shorter conguration characteristic of the more open patterns. In a completely rearward position. there is no opportunity either for expansion of the charge or for the escape of gas. The shot string, therefore, behaves exactly as it would in a true cylinder barrel.

Fig. 6 shows in graphic form the eect of varying sleeve settings in inches upon pattern percentages. Again using as an example the amount of adjustment necessary to change from a full choke or 70% pattern to a modiedor 60% pattern, it will be noted that the change is in the neighborhood of one inch, and that the range of conventional patterns spreads over approximately four and one-half inches. Obviously, with this wide range, dimensional control of the sleeve setting, either in the factory or the field, becomes a relatively simple proposition. This modification produces slightly more open cylinder patterns than that previously discussed unless the vented section of the rst modi- Iication is so proportioned that there is but little opportunity for expansion of the shot charge. When much expansion is permitted in the vented section, it may require a constriction length of from 8 inches to 10 inches to entirely overcome the eiect of realignment in the choke throat. The full choke or close pattern capabilities of this modification are substantially identical with those already discussed.

Fig. 7 shows a physical embodiment of this modication designed for attachment to any existing firearm. Referring to the drawing by characters of reference, there will be seen a cylinder barrel 3| or a choked barrel which has been cut off behind the choke to produce a cylinder barrel. Threadably attached to the muzzle is a connector 32 which has threadably secured thereon avent tube 33 provided with vents 34. The vent tube is internally threaded for its entire length and receives therein the externally threaded choke tube 35 provided With a choke throat 36 and an elongated constricted section 31 preferably at least 6 inches in length and preferably of an internal diameter not greater than that of the barrel.

Obviously, the adjustment of this model is achieved by screwing` the choke tube into the vent tube. In this way, there are effected simultaneous reductions in vent area and length of recessed section.

The embodiment shown in Fig. 8 provides diierent means for making the adjustment but is in all functional aspects the equivalent of the previously discussed embodiments of this modification. Shown in Fig. 8 is a true cylinder barrel 4I on which there is slidably received a connector bushing 42`. Threadably attached to the bushing;f is the vent tube 43 which has vents 44 formed therein. The vent tube, in turn, furnishes a mounting for the choke tube 45 which may be threadably or otherwise attached. The choke tube is bored to provide a choke throat 46 and an elongated constricted section 41 of preferably at least 6 inches in length and of the same inside diameter or slightly less than that of the cylinder bored barrel 4I. Obviously, sliding the bushing longitudinally on the barrel will vary the area of the vents directly exposed to gas escaping from the muzzle of the barrel and at the same time the eiective length of the recessed sectionf with resultsf thersame' asfthcse: already: dis'- cussed. Anky.: ventsi to( thei rearof -themuzzle of the barrelA are :not` directly exposed-.to-.eseaping gasl andftheir i effectivenesssorgreatly` reduced that. fcr-practical purposes-they may rbe dis regarded.

Itnwill :befnoted ythat this i modification presents a-fgreater effective barrelv length when set for fullchoke patterns which are primarily useful at long ranges. Thus, antimportant `boost is giyenzto accuracy at the range where accuracy is a most :important factor'.

It may also be noted'that either ofthe mod-icationsprovides-the greatest vent area and hencerthe greatest.recoil-reduction when setin fult choke position. Sincewit is the usual` practice to utilizelongrange, high velocity shot lshells fonthose targets which are bestfadapted to full choke targets,4 this -invention provides for yan equalizationv of recoil between; forl example, a longgran-geI duck? load 'and' a relatively low-pow` ered;.short yrange-Skeet load; This effect is off-considerable 'utility-with automatic shot-guns which l`are. vgenerally recoil operated and require speciali-.adjustments to compensateA for the varying recoil effects of various-special purpose loa-ds;

Thediscussionherein has been little concerned withdesigndetails and. it is not intended that the.inventiondescribed herein .shall be limited to-any particular mechanical embodiment shown. Likewise; although certainy theories of opera'- tion havel been set forth, it is' not intended that this. invention:V be limited thereby. The basic construction and the results achieved thereby have lbeen set'forth and are `demonstrably consis-tent# regardless ofethe correctness of the theory; Y. It is-intended that this invention is to be considered as limited `only as required `by the scopeof'the `claims appended hereto.

I claim:

1. In combination with a shotgun barrel, an elongated `choke section substantially coaxial: withv thebarrel and supported forwardly thereof,` said-choke 'sectionflcomprising a forwardly andy inwardly tapering choke throat which merges at its-.forward end into an. elongated tubular sectionI not substantially less thansix' inches in length and of an inside diameternot' substantially less than the-least diameter of said choke throat and not substantially greater than the inside diameter of said barrel; and gas vent means of adjustable area Adischarging laterally from betweenv vsaid barrel and the-forward end of.- said choke section.

2.1InI ycombination with a shotgun barrel an` elongated choke section substantially Icoaxialr with and forward of said barrel-andrsupported forwardly thereof, said chokeA section comprising a lforwardly and inwardly tapering choke throat .which merges at its forward end into an elon- Igatedftubular sectiony not substantially less than -s-ix:inches in lengthand of an inside diameter not substantially less than the least diameter of said choke throat and not substantially greater than the inside diameter of said barrel; gas vent means discharging laterally from between said barrel and saidchoke section; and adjustable means to regulate the degree of opening of said vents.

3.` In combination with a shotgun barrel', a ltubular member mountedv on said barrel and provided with gas vents; adjustable means to control" the degree of opening of said vents; and an elongated'choke tube mounted in substantially -coaxial relation to the barrel immediately forward of said tubular member, said choke tube comprising a .forwardly ,and inwardly' tapering.

choke` throat which merges-at iits :forward y:end in-to a tubular. section not substantiallyy less` than six. inchesinlengthi and of an inside. diameter .not substantially greater thanthe inside diameter. of said. `barreleand vnot lsubstantial-ly `less than the least diameter of saidi ychoke throat.

4. In.. combination with a shotgun `barrel, a tubular member mounted Orr said barrel `and defini/ng,v a Ichamber surrounding. the-1 muzzle ofthe barrel-gas vents inthe tubular. member; adjusteable-means tocontrol-the open areaofsaid vents; andan elongated choke tube mounted on and extending forwardly4 from isaidwtubular member in substantially coaxialfrelation to the barrel, said choke tubecomprising a lforwardly and inward.- 1ytaperingchokethroat which merges at its forward endl-into a tubularsection not` substantially lessvthan. six: inches in lengthv andy --not substantially greater-in inside diameter thanv said -barrel andl not substantially'less in insidediameter. than. theleast-diameter ofthe-choke throat. Y

5. In combination with a shotgun barrel,- ya tubulanmembermounted on said barrel andi-defining a chamber surrounding themuzzle of'said barrel ;A 4gas vents in said tubular member; adjust.- ablev means to. obstruct. the passage of. .gas through saidA vents; and l-a .choke tube -'mounted on and extendingforwar-dly from said;v member in axial alignment vwith said barrel, saidA choke-.tube having a` `forwardly and inwardly. tapering. choke` throat which` merges.. at--itsforward, small end, into a tubular section not/substantially lessthan six inches :in .length and Otan insidediameter. not substantially `greater.thantheinside diameter of saidv barrel :and notlsubstantially lessthan the least diameter of said choke throat,

6. In combination with. a..shotgun...barrel, a member defining a tubularuchamber .aligned with and. supportedby .said barrel; V.gas vent means'in the walls of. said-member.; adjustable means to enablethe exposure of.a desired area ofsaid vent means;. and a choke tube mounted on said membeninu alignment said. choke tube comprising a forwardly andinwarcllfy tapering .chokev throat which merges at its forward, small end, into .a cylindricalv tubular section at least six inches, in length and having an, inside diameter not substantially greater than the inside diameter of said barrel-and not substantially less than the leastA diameter of As'aidvchoke throat.

7. In combination with a .shotgun barrel, a tubularmember. mounted on said barrel and eX- tendingv forwardly from the muzzleA thereof; gasvent means in` the. tubular member; sleeve valve meansy adjustably mounted on. the tubular member to control the exposed area of said vents; andv an elongated choketube mounted on said tubular member andy extending forwardly therefrom, said choketube-comprisinga forwardly and inwardly tapering choke'` throat which. merges at its for-V ward end into a ltubular section not substantiallyI less than. sixinches in. length and having an insideidiameter not substantially greater than the insidev diameter ofV the barrel and not substan.l tially` lessthan the least diameter of the choke throat.

8. Inv combination with a shotgun barrel, .a memberI definingan enlarged tubular chamber aligned with said barrel and of adjustable length forward of the endof said barrel; gasvent means in thewall of said member, said gas vent meansV being progressively reduced in exposed area as the'length ofcsaid. tubular chamber is reduced;-

lation to said barrel, said choke tube comprising a forwardly and inwardly tapering choke throat which merges at its forward end into a tubular section not substantially less than six inches in length and having an inside diameter not substantially greater than the inside diameter of the barrel and not substantially less than the least diameter of said tapering choke throat.

9. In combination :with a shotgun barrel, a member defining an enlarged tubular chamber aligned with said barrel so constructed and arranged that the length of said chamber forward of the end of the barrel may be adjusted; gas vent means formed in the wall of said member; means to progressively reduce the exposed area of said vents as the length of the chamber is reduced; and a choke tube having a forwardly and inwardly tapering choke throat merging into a constricted cylindrical bore mounted on and extending forwardly from said member in alignment with said barrel, the cylindrical bore of said choke tube being not less than six inches in length and of an inside diameter not substantially greater than the inside diameter of said barrel and not substantially less than the least diameter of said tapering choke throat.

10. In a construction for controlling the pattern of a shot charge propelled through a shotgun barrel by the action of a confined gaseous medium acting upon the rear face of said charge, the combination of a concentrating means for gradually reducing the diametral dimension of said moving shot charge, tubular means positioned adjacent said lconcentrating means in the direction of travel of said shot charge arranged to maintain the diametral dimension of said shot charge substantially constant at a dimension not substantially greater than the least diameter of said concentrating means for a distance not substantially less than six inches, and venting means for controlling the extent to which said gaseous medium maintains pressure on the rear face of l0 said shot charge while said charge is traversing said tubular means.

11. In a construction for controlling the pattern of a shot charge propelled through a shotgun barrel by the action of a confined gaseous medium acting upon the rear face of said charge, the combination of a concentrating means for gradually reducing the diametral dimension of said moving shot charge, tubular means positioned adjacent said concentrating means in the direction of travel of said shot charge arranged to maintain the diametral dimension of said shot charge substantially constant at a dimension not substantially greater than the least diameter of said concentrating means for a distance not substantially less than six inches, and adjustable venting means for controlling the extent to which said gaseous medium maintains pressure on the rear face of said shot charge while said charge is traversing said tubular means.

GILBERT E. HUTCHINSON.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 618,901 Peterson Feb. 7, 1899 827,259 McClean July 31, 1906 1,598,360 Pavek Aug. 31, 1926 1,605,393 Cutts, Jr NOV. 2, 1926 2,098,617 Cutts, Jr Nov. 9, 1937 2,191,484 Hughes Feb. 27, 1940 2,335,138 White Nov. 23, 1943 2,340,821 Russell Feb. 1, 1944 2,428,232 Limon Sept. 30, 1947 FOREIGN PATENTS Number Country Date 811,377 France Jan. 14, 1937 Certificate of Correction Patent No. 2,484,998 October 18, 1949 GILBERT E. HUTCHINSON It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 1, line 10, for the Word shoot read shooting; column 2, line 31, for short read shot;

and that the said Letters Patent should be read With these corrections therein that the same may conform to the record of the case in the Patent Oce.

Signed and sealed this 14th day of February, A. D. 1950.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.

Certificate of Correction Patent No. 2,484,998 October 18, 1949 GILBERT E. HUTCHIN SON It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 1, line 10, for the Word shoot read shooting; column 2, line 31, for short read shot; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case n the Patent O'ce.

Signed and sealed this 14th day of February, A. D. 1950.

THOMAS F. MURPHY,

Assistant ommz'ssoner of Patents. 

